Stored program control communication switching systems comprise some form of intelligence which controls switching functions in response to a program stored in memory. Historically, such systems included a single processing entity for the control of the entire system. As technology and system design evolved, it was found desirable to separate certain routine functions from the main processing entity to save its processing time for more complex system functions and decisions. Today, systems are being designed which also separate some of the more complex system functions and decisions into several intelligent processors. Throughout the evolution of switching system control strategies, changes have occurred in the way the various processing entities intercommunicate. Some systems have provided a separate controller bus structure to be used for all communication among the processors. Other systems have utilized the normally speech conveying communication paths of the switching system to provide communication paths between the distributed system processors and a central controller which interprets control information and directs the overall operation of the switching system.
The tolerance of system faults is necessary in telephone switching systems in order to maintain system integrity. As the functions performed by the distributed processors of a telephone switching system have become more important to call completion, and the processors have become more autonomous in this operation the tolerance of faults associated with those distributed processors has become very difficult to achieve. In those cases where the only communication link between the central intelligence and the distributed processors is controlled at least in part by those distributed processors, remotely effectuating fault tolerance is extremely difficult.
The present invention is an arrangement for remotely controlling the distributed processors of a telecommunication system in which a central intelligence communicates with the distributed processors through a portion of the telephone switching network.